A Novel Method of Detecting Measurement Uncertainty of Voltage Deviation

2013 ◽  
Vol 805-806 ◽  
pp. 688-692
Author(s):  
Xin Fang ◽  
Xue Liang Huang ◽  
Yan Zhu

Nowadays, there are various devices to detect the power quality of AC grid, where uncertainty of voltage deviation is an important parameter to investigate the power quality. National standards specify several sinusoidal waveforms to detect it, usually implemented into the detecting devices. But these waveforms are not enough and a novel method of detecting measurement uncertainty of voltage deviation is proposed in this paper. A series of detection waveforms are designed using this method. The simulation results verify that the method is available to measure uncertainty of voltage deviation more accurately. Moreover, it can be used to justify whether the basic measurement time interval of voltage deviation meets IEC standard requirements.

2018 ◽  
Vol 6 (5) ◽  
pp. 177-189
Author(s):  
P.K. Olulope

This paper examines the power quality of Ado-Ekiti metropolis in Ekiti State, Nigeria. The metrics of power quality includes: disturbances such as interruptions, voltage sags, spikes and momentary losses, power harmonics, and voltage unbalances with intrinsic effects on the efficiency and performances on the electric equipment. The necessity for this paper is the fluctuations of voltage supplied to the consumers by the distribution company in Ekiti State. These have significant effects on the power delivered to consumers ‘appliances, quality of their lives and the development of the society at large. The quality of voltage of each consumer in the selected areas were measured with the aid of digital multimeter which was compared with the standard nominal voltage of 240V, voltage deviations were evaluated through the use of standard mathematical equation and linear regression model was employed on the calculated voltage deviation with day and time used as inputs and the voltage deviation as the output. The implementation of the modelling was achieved through the use of Microsoft Excel data tool. The power quality for areas1, 2, 3 for the hours under consideration were poor with respect to R2 range of above 0.5 but better than that area 4 with R2 value of less than 0.5.The results were compared and recommendations were made with the view of improving the power quality in the metropolis.


2013 ◽  
Vol 860-863 ◽  
pp. 2572-2577
Author(s):  
Ai Qiang Pan

Metro Transit Railways (MTRs) provide pubic convenience, but also bring power quality impact on power grid. Based on the field measurements, this paper discusses and analyzes the power quality characteristics of MTRs in Shanghai. In the terms of harmonics, voltage flicker, voltage unbalance, voltage deviation, frequency deviation and transient events, numbers of indicators are investigated to explore the power quality characteristics and existing problems of MTRs. Although harmonics are still the main problem impacting of MTRs, other power quality indicators comply with the restriction of national standards. Besides, the line charging reactive power is a common issue and transient power quality events occurs intermittently. The paper presents the corresponding proposal, which is instructive in power quality management of MTRs in cities similar as Shanghai. .


2013 ◽  
Vol 805-806 ◽  
pp. 667-672
Author(s):  
Yan Zhu ◽  
Xue Liang Huang ◽  
Xin Fang

Power quality monitoring products are very popular to monitor and control the power quality in recent years. The uncertainty of voltage unbalance is an important parameter designed in these monitoring products. Some standards specify several sinusoidal waveforms to detect the uncertainty of voltage unbalance. But these waveforms seem not enough and some manufactures do not follow the standards to design the detection process. So this paper proposes a method of detecting the supply voltage unbalance accuracy and gives some detection waveforms for uncertainty of voltage unbalance. The simulation results show good agreement with the IEC standards.


2014 ◽  
Vol 687-691 ◽  
pp. 3162-3165
Author(s):  
Li Sheng Li ◽  
Shi Dong Zhang ◽  
He Jin Liu ◽  
Xing Quan Ji ◽  
Gui Bin Liu ◽  
...  

Wind generation can affect the power quality of power supply system in a certain extent at the same time of energy conservation and emission reduction. In order to study the power quality problem of distribution network with wind power embedded, several indices of power quality are defined in this paper, and the doubly fed wind turbine model is established in detail. The voltage deviation, system frequency, and harmonic distortion rate are analyzed based on the simulation data outputted by PSCAD.


2021 ◽  
pp. 71-75
Author(s):  
Н.П. Тишанинов ◽  
А.В. Анашкин ◽  
К.Н. Тишанинов ◽  
Х.Д.Д. Альшинайиин

Представлены результаты исследований физико-механических свойств компонентов зерносмеси, динамики и качества выделения примеси из неё в зависимости от скоростного режима работы триера (n) и угла подъёма верхней кромки передней стенки выводного лотка (γn). Подтверждён лавинообразный характер выделения проса из ячменя в первых интервалах времени измерений за счёт эффекта динамической сегрегации примеси в циркулирующих слоях зерносмеси. Положительный вектор сегрегации проса (вниз – к ячеистой поверхности) объясняется значительной его насыпной плотностью, гладкой поверхностью – угол естественного откоса составляет 20,3° (в 1,8 раза меньше, чем у ячменя), компактными размерами зерновок и их округлой формой. Установлена высокая степень влияния на интенсивность выделения примеси скоростного режима – при приросте n на 12,5% (от 40 до 45 об/мин) выделенная масса примеси в первом интервале времени измерений (tи = 5 с) увеличилась на 125%. При γn= 35° степень выделения примеси (и остаточная засорённость) обеспечиваются на высоком уровне стандартной длиной ячеистого цилиндра (l = 2,2 м) во всём диапазоне скоростного режима работы стенда n = 40…55 об/мин. С ростом γn до 45º сужается диапазон скоростного режима работы по качественным показателям до n = 45…55 об/мин, а при γn= 55º качество работы обеспечивается только при n = 50…55 об/мин. При γn= 45…50º и n = 50…55 об/мин 100%-ное выделение примеси обеспечивается за 30…35 с смещения сегмента зерносмеси по длине ячеистого цилиндра. При этом его рабочая длина используется лишь на 55…64%. Технологические потери на всех исследуемых режимах работы не превышают 0,3% и носят случайный характер, что объясняется неопределённостью условий выброса зерновок ячменя ячеями. The research results of physical and mechanical properties of grain mixture components, dynamics and quality of impurity extraction from it are presented depending on the speed mode of operation of the trieur (n) and the lifting angle of the upper edge of the front wall of the lead tray (γn). Avalanche-like character of millet separation from barley in the first intervals of measurement time is confirmed due to effect of dynamic segregation of impurity in circulating layers of grain mixture. The positive vector of millet segregation (down to the cellular surface) is explained by its significant poured density, a smooth surface – the angle of friction is 20.3° (1.8 times less than that of barley), compact bruchid sizes and their rounded shape. A high degree of influence on the rate mode impurity release intensity was established – at an increase of n by 12.5% (from 40 to 45 rpm), the extracted impurity mass in the first measurement time interval (tи = 5 s) increased by 125%. At γn = 35°, the degree of impurity release (and residual content of impurities) is provided at a high level by the standard length of the cellular cylinder (l = 2.2 m) in the entire range of the speed mode of the bench n = 40...55 rpm. With an increase in γn to 45º the range of the high-speed mode of operation is narrowed to n = 45...55 rpm, and at γn = 55º the quality of operation is ensured only at n = 50...55 rpm. At γn = 45...50° and n = 50...55 rpm 100% impurity release is ensured by 30...35 second with displacement of the grain mixture segment along the length of the cellular cylinder. At the same time, its working length is used only on 55...64%. Technological losses in all investigated modes of operation do not exceed 0.3% and are random in nature, which is explained by the uncertainty of the conditions for the release of barley bruchids by cells.


2013 ◽  
Vol 647 ◽  
pp. 935-938
Author(s):  
Marian Gaiceanu ◽  
Adriana Burlibasa ◽  
Cristian Eni ◽  
Mihaita Coman

Grid-connected power converters are controlled by the current loop, the voltage being delivered by the grid. The proposed state feedback current control has three components: the state feedback, the forcing component to achieve the desired state x1 and the compensating feed forward of the perturbation. Moreover, the control of the power converter, through the external DC-link voltage loop, and internal current loop, assures zero steady state error, and power quality performances. In order to prove the quality of the proposed control, a regenerative load has been used, and the corresponding simulation results are provided.


2015 ◽  
Vol 713-715 ◽  
pp. 1335-1342
Author(s):  
Zhi Qiang Gao ◽  
Hua Yu Chu ◽  
Liang Meng ◽  
Si Qing Sheng ◽  
Zhong Ji Sun ◽  
...  

As distribute power generation and micro-grid technology develops, more and more researchers attach importance to the problems of power quality in micro-grid, especially the problem of harmonic. This paper describes the impact and harm harmonic has on the power quality of the power grid. It introduces a revised method of managing micro-grid harmonics which uses an active power filter (APF), and the control method of APF is different from the traditional one. It also establishes the simulation model of micro-grid, analyze the simulation results and experiment in actual micro-grid to verify the effectiveness of the proposed method.


In this paper investigates the improve power quality of RES with adopting smart loads in detail. In wind energy conversion system permanent magnet synchronous generator (PMSG) is employed is employed to get better simulation results over induction generators. Obtained validate MATLAB simulation results considering variable speed variations periodically. Variable wind power production needed in distribution stochastic and periodic power variations to reach load demand. This load management maintenance is highly requires to maintain power quality. This load management is allocated employing smart loads (SLs), capacitor banks and critical loads (Electrical spring).From various case studies, it is found that SLs are effective in improving the voltage profiles of the test feeder


2021 ◽  
Vol 309 ◽  
pp. 01009
Author(s):  
M. Vasu ◽  
D. Lenine ◽  
J. Surya Kumari ◽  
T. Suresh Kumar

Harmonics produced by distributed power generation systems (DPGS) is a main power quality issue, particularly due to the number of these systems connected to the grid is always increasing. This means that, it is significant to control the harmonics caused by these inverters to limit their contrary effects on the grid power quality. This paper has proposed a new proportional current controller (P Resonant Current Controller) with selective harmonic compensator for grid connected photovoltaic (PV) systems. The proportional resonant current controller (PRCC) can have a significant effect on the quality of the current supplied to the grid by the PV inverter, and hence it is essential that the controller provides a high-quality sinusoidal output with negligible distortion to avoid generating harmonics. The effectiveness of the proposed framework has been verified using simulation results in MATLAB/Simulink.


Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2118
Author(s):  
Pengcheng Yin ◽  
Jin Xu ◽  
Lingna Yue ◽  
Ruichao Yang ◽  
Hairong Yin ◽  
...  

In this paper, a novel method, named PM-E, to focus the sheet electron beam (SEB) is proposed. This new method consists of a periodic magnetic field and an electrostatic field, which are used to control the thickness and width of the SEB, respectively. The PM-E system utilizes this electrostatic field to replace the unreliable By,off, which is a tiny transverse magnetic field in the PCM that confines the SEB’s width. Moreover, the horizontal focusing force of the PM-E system is more uniform than that of the conventional PCM, and the transition distance of the former is shorter than that of the latter. In addition, the simulation results demonstrate the ability of the PM-E system to resist the influence of the assembly error. Furthermore, in the PM-E system, the electric field can be conveniently changed to correct the deflection of the SEB’s trajectory and to improve the quality of the SEB.


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